New ammonite finds indicate that the sea transgressed over the crystalline basement of Milne Land, East Greenland, in Boreal Bathonian time and not in Middle Oxfordian as previously thought. A coral (Enallocoenia callomoni Beauvais) occurring in the transgressive Upper Bathonian deposits is the first hermatypic coral known from the Boreal Middle Jurassic. The unusually complete Boreal Upper Callovian-Oxfordian-Kimmeridgian ammonite succession is described; the faunas include remarkable occurrences of submediterranean genera (Hibolithes, Pachypictonia, Streblites). Finally, the sedimentary and tectonic evolution of Milne Land and adjacent areas in Jurassic time is outlined. It is shown that the area was characterized by gentle block-faulting.
The Jurassic-Lower Cretaceous sediments of Jameson Land and Scoresby Land are divided into seven formations. They comprise from bottom to top: Kap Stewart Formation of Rhaetian-Liassic age; Neill Klinter Formation of PliensbachianToarcian age divided into three members; Vardekløft Formation of ?BajocianMiddle Callovian age redefined and divided into three members; Olympen Formation of Upper Callovian-Middle Oxfordian age designated as a new formation; Hareelv Formation of Upper Oxfordian-Middle Kimmeridgian age designated as a new formation; Raukelv Formation of Upper Kimmeridgian-Upper Volgian (Lower Ryazanian?) age designated as a new formation and divided into three members; Hesteelv Formation of Ryazanian age designated as a new formation and divided into two members. The six lower formations together comprise the Jameson Land Group. The main facies types are described. They comprise black shales, shaly siltstones, horizontally bedded sandstones, ripple-laminated sandstones, massive-bedded sandstones, medium- and large-scale cross-bedded sandstones, black shales with lenticular sand-bodies and coals. A general interpretation of the changing depositional regimes throughout the Jurassic and Lower Cretaceous of Jameson Land and Scoresby Land is given. The interpretation is based on the spatial distribution of the different facies types, on longitudinal profiles, and on investigations and measurements of cross-bedding, parting-lineation, grain sizes and sand-shale ratios. The exact geographical position of the borderlands and thus of the source areas of the sediments are rarely known but the predominance of very coarse sediments and the large-scale sedimentary structures indicate a position very near the coast.
The upper part of the jurassic to Lower Cretaceous succession of Milne Land, described in the present paper, represents an unusually complete, highly fossiliferous sequence of Kimmeridgian, Lower and Middle Volgian and poorly fossiliferous ?Lower Valanginian to Hauterivian deposits. On the basis of some 50 recorded sections the succession is described with respect to lithology and fossil content and placed within a lithostratigraphical frarnework. The Upper Callovian – Middle Volgian Kap Leslie Formation (overlying the Charcot Bugt Formation) is divided into eight members, the upper four of which are described in detail (Gråkløft Member, Krebsedal Member, Pernaryggen Member and Astartedal Member), while the Middle Volgian – Hauterivian Hartz Fjeld Formation above is divided into two members (Hennigryggen Member and Pinnadal Member). A succession of 34 ammonite faunas has been recorded from the Kimmeridgian to Middle Volgian succession of the area. The Kimmeridgian to Lower Volgian faunas match British faunas so closely that the standard zonation of Great Britain can be used. The 17 faunas of the Middle Volgian are closer to successions of northern Russia and Siberia, and the succession has been made the basis of a new regional zonation of nine standard zones for the Boreal Province. One Lower Cretaceous ammonite fauna has been recorded, having ?Early Valanginian age and uncertain affinities. The faunal horizons of Volgian ammonites from Milne Land figured by Spath (1936) in his classical monograph have been determined. Stratigraphically important species found since then have been described elsewhere (Callomon & Birkelund, 1982). The three main areas of outcrops, the Hartz Fjeld area, the Kronen area and the Bays Fjelde area, are correlated in detail on the basis of ammonite occurrences. The depositional environments and tectonic evolution of the Milne Land area are outlined. Some key sections of particular stratigraphical importance are described in an appendix.
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